Fuel pump



Jan. 13, 1931.11. ji'gg-Nu* 11,788,836 FUELrUMB l Filed May 7, 1928 amg@ Pleated Jan. 13, 1931 UNITEDQSTATES vMTEN15ol-"l-lcl I msx N. imrrr,

or rim, mentalen, Assieme ro A; c snm: -rLUG conm, or :Linn-'moment' a company or moineau Y .Y

Application, filed` Hay 7,

, This invention relates to pumps and more specifically to animprovement in flow pres sure pumps useful in supply'ingffuelto the carburetorsof internal com ustiomengines'. The invention, has forl its' objectrlja pump with an improved mechanism fory providing the suction `and discharge strokes. Another object is to produce the suction str okeby a reduction of gaseous., pressure `to.v thereby overcome a spring' tending atall times to provide a ydischarge'str-oke... Other objects andadvantages,- such asei'ciency in operation, quietness inaction and long life, will be appreciated fromareadingof. the speci-Vv ication and an examination of theaccom-i panying drawing.I V r Inthe drawing: Figure 1 is a section the motorblock of an internal combustion 2o en ne and ofthe fuel'vpump used therewith; igures 2,3 and 4aresfections on lines 2 -2, 3.--3 and 4 4 respectively ofY Figure 1. Referring tothe drawing by Yreference characters, mimeralr 5 represents a part v,of an internal combustion engine.l There is shown a cylinder 7, a valve tappet 9the`l`atter actuated by camshaft 11. The crankcase wall 13 has anyopening 15- which isftovlbe closedy by a yfuelfpump constituting the sub,- so'ject matter. of this application. jNo further description is given *ofv the internal combustion engine forthe reason that the .invention relates only to the pump by'. which. fuel is su l plied and not to the engine'itself.;Y a e pump is vcomposed of two zparts, a pump body17and a cover 19. vThepump body 17 `is formed with a horizontal,portion which is bored out toforma cylinder 21. y This parthas avflange 23 engaging the crankcase wall and is `securedfthereto by suitable fastening means A25, as f shown in Figure 4. The'extreme end lof, pump member 17 extends beyond the ange 23 within the opening 15 and aids in positioning the pump body. The cylinder 21 ,extends through this extreme end, and ywithin the cylinderA is slidably mountedy a piston. 27. The inner endI of the pistony is enlarged as at 29 and the enlarged end vis engaged by a cam 31 carried by the shaft 11. VAsA shown 'throught pail ifv 188s. serial No. 875,782. i

in .thedrawing, the pump' is positioned so v 11, Ity will be understood that the pump i .may be otherwise located. The pump may i A. be, positioned, forl yexample sothat the piston'may" be in the* path ofmovement'of a camon the "water pumpjqshaft, for on the :forwardlyy YprojectingV end of the crank- The drawing Lillustrateswhat is now be-` lieved to be a vvery desirable arrangement wherein the `pump piston 27 is engaged by a cam on ,theI camshaft,l which shaft is used to actuate the valves `f the engine. The piston is normally.' urged' against the camshaftby a coil spring 35` surrounding the piston and fin abutment'with wall 13 Aand with'the enlarged end 29 of the piston. In parallelfrelation with the cylinder is the passage 37 of smaller diameter' than the piston. The passagef37 v also `conirnunicates withthe crankcase, andv at 39 the pump body is bored to providean'lopening toy passage 37 and a reduced opening 40 to the cylinder 21. A circular disc valve 43 normally closes the communication between cylinder 21fand thev passage 37 'being' held against the shoulder between the passages 3 9 and '40 by a 'spring 45. V"This spring engages the valve 43`and anfabutment 47 which is threaded into the opening 39.v yThe valve 43 is circular in shape andwhen moved downwardly (Figure 1 opens the angular {passage'between the cylinder 21 and the passage v37. For the urpose of providing lubrication, the piston is provided with 'circumferential grooves.,49. Oil will be drawn from thel crankcase into these grooves and lubricat'e the cylinder wall.' The excess lubricant will be returned to ,the crankcase through the -valve 43l and the passage 37. v The substantially circular cover member of the pump 19 is secure to the pum `body 17 by fastening means 51. Between t e body'and the' cover is clamped the diaphragm 53'which y i is preferabl of /exible fabric.r Thebody portion of t e pump 17 above theclosed end 1 of cylinder 21 1s fiaredout, as illustrated, to Yform a chamber 55. 1 'lhe walls ofthe chamber have an abutment 57. This abutment is intended to engage at times a metal disc 59 secured together with another metal disc 61 on the other side of the diaphragmv by fastening means 62. The downward movement of the diaphragm producing the suction stroke is stopped by the engagement of the lower disc 59 with the abutment 57. Between the cylinder 21 and the chamber 55 is a pas-' pump chamber 65. A spring 71 normallyv holds a disc valve member 7 2. preferably hexagonal in shape as shown in Figure 3, against a 'threaded plug. 73. This spring is capable of being overcome by reduced pressure within f the pump chamber,ithereby permitting the valve 72 to move downwardly and admit fuel from the opening 67 into the pump chamber 65. A discharge `valve is formed by a plug 75, a spring 77, an hexagonal valve disc 79 and an opening 81. It will be understood that the o ening 81'is to be connected to the float cham er of the carburetor and that for that'purpose, a suitable conduit will connect the opening 81 with the carburetor.

In operation, let it be assumed that the arts arein the position shown by Figure 1. The movement of the piston 27 to the right, which movement has been produced by spring 35, has tended to increase the volume and decrease t-he atmospheric pressure within the chamber 55 and the closed end of cylinder 21 beyond the piston 27. Spring 63 has resisted the downward movement of the diaphragm as the diaphragm tended to move down in its attempt to prevent the development of vvacuum in chamber 55.l At the end of the stroke of the piston 27 to the right, a balanced condition lexists in which the unbalance between the atmospheric pressure above the diaphragm and the sub-atmospheric pressure below the diaphragm is alanced by the tension of spring 63. In its downward movement, the dia hragmhas executed a suction stroke and rawn fuel into the pump chamber 65 through the valve 72. Thereafter, the cam pushes piston 27 to the left. This movement disturbs the balance whereby the sub-atmospheric condition in the chamber 55 is holding spring 63 in restraint. As the piston 27 moves to the left, the reduced pressure in chamber 55 is relieved and spring 63 is released and is free to execute a discharge of fuel through opening 81 and deliver the fuel to the carburetor. The delivery of fuel to the carburetor will be controlled by theV carburetor fioat valve and by the feeding pressure determined by the calibrated s ring 63. If in any two successive strokes me of suction and one of discharge as described above) the fuel demands of the carburetor are such that more fuel is drawn into the pump chamber than can be discharged by the action of spring 63, spring 63 then has a built-up pressure. The added air pressure in chamber 55 occasioned by the movement of piston 27 to the left and the failure of the diaphragm to move upwardly to an extent commensurate with the movement of piston 27 is relieved by passing valve 43 and the passage 37, which communicates with the cran'kcase. It will therefore be seen that under certain conditions of operation, spring 63'may assume a degree of pressure such that the diaphragm disc 59 will engage abutment 57 after which piston 27 may reciprocate to and fro without causing any pump action. Use of fuel by the carburetor will at once reduce pressure in the pump chamber and will, in an obvious manner, again start the pump action. The grooves of the piston will serve to carry oilfrom the crankcase, lubricate the cylinder wall, and excess oil will be restored to the crankcase through the valve 43 and the passage 37.

A fuel pump constructed as described will provide fuel to the extent demanded by the carburetor. It is noiseless, spring 35 holding the piston 27 at all times on the cam and there being no mechanical connection between the diaphragm and the piston 27- It will have long life since the diaphragm is moving only when active t'o supply fuel and its movements are then limited in proportion to the fuel demanded.

I claim:

1. A fuel pump for gas engines comprising a body' having inlet and exhaust valves, a movable pump member serving with said body to form a first variable volume pump chamber, a second member movable indevpendentlyvof the movable pump member,

means associated with said movable pump member and said second member forming therewith a second variable volume chamber, resilient means to move said movable pump member to make a discharge stroke, means to move said second movable member to increase the v olume of said second chamber, and independent engine operated means to move'said second member in a direction to` decrease thevolume of the said second chamber.

2. The invention defined by claim 1, said resilient means Vand the variable ressures in said second chamber resulting rom movements of said second movable member both operating upon one and the same side of said movable pump member.

3. The invention set forth in claim 1,

:,vsasse said second movable member .being a recip rocating iston. l

4. The invention set forth in claim 1, said means to move the second movable member in a direction to increase the volume of the second chamber being a resilient spring.

5. A pump for fluids comprising a ilexible pumping element, means associated therewith forming closed chambers, one'on each side thereof, inlet and dischar e valves communicating with one of said c ambers,

means movable independently of said flexible pumping element and reciprocable in the second of said'chambers, a spring operable upon .said flexible element to produce a discharge stroke, mechanism'to move said reciprocable means in opposite directions whereby the said spring an the varying pressures in the sec'- ond chamber resulting rom movements of the reciprocable means produce pumping action, y. said mechanism including a resilient element to increase the volume of the second chamber, and opposed power-operated means to decrease the volume of the second chamber.

6. In combination with an engine'having- Y a crank case, acam shaft therein, a cam on said shaft, a pump positioned adjacent said crank case, said pump comprisinga body, a vibratory mem er dividing said body in a rst pump chamber and a second chamber, Y inlet and exhaust valves in said pump cham-A 7. The invention definedrby claim` 6, said body having a passage therein communicating with said crank case, and a relief valve opening from saidsecond chamber to said passage.

In/` testimony whereof I aix my signature.

FRANK N. NUTT. 1 i

amber, p 

